The invention relates to a diode comprising an electrically insulating envelope, within which a semiconductor wafer with a pn junction is enclosed between metal studs, and current conductors which are connected to a respective metal stud and project beyond the envelope, the metal studs being sintered bodies mainly comprising tungsten and a metal promoting the sintering process; the invention further relates to a metal stud suitable for use in such a diode. Such a diode is known from Japanese Patent Application 58-75862 A (Touchou Kinzoku K.K. 1983-5-7).
Before sintering, less than 0.5% by weight of Ni has been added to the tungsten of the studs of the known diode. The addition renders it possible to sinter the studs at a lower temperature (1800.degree.-1950.degree. C.) than is the case in the absence of Ni. Without the addition of Ni, the sintering process has be effected at a temperature at least 2200.degree. C. in order to be able to accomplish the operation within a reasonable period of about half an hour.
However a disadvantage of the use of Ni as sintering activator is that it leads to a considerably coarser structure of the sintered body, as is apparent from photographs in the aforementioned Japanese Patent Application. It has been found that, when the structure becomes coarser, this leads to a reduction of the mechanical strength of the metal studs.